mu óf 6E5P

[Ryssen]

what is the mu of 6E5p,can`t find it in any pdf.

 

[Bigun]

Because it is a tetrode; it only has a mu if wired up as a triode, in which case around 30 to 35

 

[Ryssen]

Thanks I learned sommething new today then.
So a Tetrode doesnt have an amplifying factor then.

 

[rufus74pz]

Hello,
S=30.5±6.5mA/V
Ri=8000Ω
µ=S*Ri
Piotr

 

[Ketje]

Thanks I learned sommething new today then.
So a Tetrode doesnt have an amplifying factor then.

Tetrodes (and pentodes) have a µ too, µ=SxRi.
The gain is S x (Ra x Ri) / (Ra + Ri) that is S multiply by Ra//Ri.
Since usualy Ri >> Ra ( Ri is very big ) the gain is ~S x Ra. Making the µ not very interesting.
Mona

 

[Bigun]

what makes mu interesting in a triode is that the internal resistance and transconductance often vary in opposite fashion with each other with anode current so that mu is relatively stable and hence gain is less dependent on signal current and distortion is minimized.

The 6e5p has a sensitive screen grid, feedback from the anode is very effective and when wired as a triode it is superbly linear compared with most ‘real’ triodes.

It’s high transconductance means it is sensitive to wiring parasitics which requires care in layout / lead dress and use of stopper resistors to avoid parasitic hf oscillations which might otherwise lend harshness to the sound.

 

[RajkoM]

You can see MU for each tube and for each operating point from tube curves diagram.
You have an example here in post No. 104 :

Vacuum Tube SPICE Models

For pentode curves, the second point is the end of the knee for Ug1 = 0V.

Best DIYing